1. Technical Field
The present invention relates to an analysis apparatus and an electronic device.
2. Related Art
Recently, a demand for medical diagnosis, food inspection, or the like has increased greatly, and there has been a need to develop compact and high-speed sensing techniques. Various sensors commencing with an electrochemical method have been considered, and an interest with respect to a sensor using a surface plasmon resonance (SPR) has increased because integration is possible, the cost is reduced, and any measurement environment may be used. For example, a technology which detects a presence or absence of adsorption of a substance such as a presence or absence of adsorption of an antigen in an antigen-antibody reaction by using surface plasmon generated in a metallic thin film disposed on a total reflection prism surface has been known.
In addition, a method is also considered in which Raman scattering of a substance attached to a sensor portion is detected by using surface enhanced Raman scattering (SERS), and the attached substance is determined. SERS is a phenomenon in which Raman scattering light is enhanced 102 to 1014 times in a surface of metal in a nanometer scale. When a target substance which is in a state of being adsorbed onto the surface is irradiated with excitation light such as laser, light (Raman scattering light) having a wavelength which is slightly shifted from a wavelength of the excitation light by vibration energy of the substance (molecules) is scattered. When the scattering light is subjected to spectroscopic processing, a spectrum (a fingerprint spectrum) inherent to a type of substance (molecular species) is obtained. By analyzing a position or a shape of the fingerprint spectrum, it is possible to determine the substance with extremely high sensitivity.
It is preferable that such a sensor has a great enhancement degree of light on the basis of surface plasmon excited by light irradiation.
For example, in JP-T-2007-538264, a mutual interaction between localized surface plasmon (LSP) and surface plasmon polariton (SPP) is disclosed, and some parameters of a gap type surface plasmon polariton (GSPP) model are disclosed.
The GSPP of JP-T-2007-538264 has a dimension in which a size of particles causing a plasmon resonance is 50 nm to 200 nm, a periodic interparticle interval is shorter than an excitation wavelength, and a thickness of a dielectric body separating a particle layer from a mirror layer is 2 nm to 40 nm, and is in a regular array of plasmon resonance particles which are densely filled by an interparticle interval obtained by adding 0 nm to 20 nm to a particle dimension.
However, in a sensor having a structure disclosed in JP-T-2007-538264, the thickness of the dielectric body separating the particle layer from the mirror layer is 2 nm to 40 nm, and according to a consideration of the inventors, it is found that a peak of an electric field enhancement degree in wavelength dependent properties (an enhancement degree spectrum or a reflectance spectrum) is broad, but an enhancement degree which is totally low and insufficient is obtained. In addition, in the sensor disclosed in JP-T-2007-538264, it is found that when a dimension of a plurality of particles is uneven (when a variation occurs), a wavelength having a peak in the enhancement degree spectrum is greatly shifted.